The ransomware hit mostly Windows 7 and Windows XP machines, and for good reason. Its spread mechanism was targeting a vulnerability in Windows’ Server Message Block (SMB) on port 445, which mainly impacted those platform iterations.

The exploit was made public a month after Microsoft released a patch for the vulnerability it targets, but hundreds of thousands of systems continue to be vulnerable today, Avira says. An emergency patch was also released for Windows XP.

The unpatched systems remain exposed to any malware that abuses the EternalBlue exploit and, as Avira senior virus analyst Mikel Echevarria-Lizarraga points out, many of these systems are serially infected.

“There are still significant numbers of repeatedly infected machines more than a year after WannaCry. […] Our research has linked this to Windows machines that haven’t been updated against the NSA Eternal Blue exploit and are an open target for malware,” he says.

The number of unpatched systems, he reveals, is very high, but there’s an explanation for that. Many of the systems that have been infected multiple times were found to run activation cracks. This means that they did not receive Microsoft’s patches.

Without the official patch, users should turn off the older SMB1 protocol entirely on these machines to stay protected, the security researcher says.

Avira says they decided to take this security measure on the machines they found to be missing the patch and that this led to the discovery of around 300,000 computers affected by the issue.

Avira says they are deactivating the vulnerable protocol on around 14,000 systems each day and that the protective measure appears to be paying off.

“The strategy is working. Once the SMB1 protocol is deactivated, we don’t see the same machines affected again and again with this problem,” he says.

The top 10 impacted countries, Avira reveals, are Indonesia, Taiwan, Vietnam, Thailand, Egypt, Russia, China, Philippines, India, and Turkey. The numbers are in line with the findings of studies from Statista on the use of unlicensed software, Avira’s Lyle Frink says.

According to these studies, the unlicensed software rates are of around 52 – 60% outside the United States and the European Union. In these areas, the rates are of only 16% and 28%, respectively.

“Unlicensed software is usually unable to get the latest patches against vulnerabilities such as EternalBlue,” Frink underlines.